The present invention relates generally to parking brakes for rail vehicles and more specifically to a parking brake with an actuator, and a force multiplier that is connected to a brake cylinder piston which applies and releases the brakes on a rail car.
The prior art discloses a number of parking brake systems for rail vehicles. Some of the parking brake systems operate independently of the overall brake system for the train and others are integrated with the overall brake system, particularly by using the main brake cylinder that operates the train""s brakes.
In general, brake systems for rail vehicles are pneumatically (air) operated. The brake system includes a brake cylinder with a piston rod to operate the brake shoes to engage the rail car wheels and brake the rail car. The brake cylinder receives a signal to apply the brakes and generally has a spring return to release them. The signal or force to activate the brakes is generally multiplied by some sort of lever that is located between a brake cylinder actuator and the brake shoes. Other brake cylinders may be spring applied and air released.
Most rail cars have a manually-operated parking brake that applies the wheel brakes. Generally, for truck-mounted brake systems, which are well-known in the art, one end of the brake cylinder has a piston rod output that is connected to levers or similar elements which connect the brake cylinder to the brake beams. Furthermore, as part of the parking brake system, a combination of chains and cables are generally used to connect the brake cylinder to a manually-operated actuating device. That connection often includes a multiplier lever. The multiplier lever is connected to a convenient location on the rail car.
The prior art also discloses an electropneumatic controlled parking brake, that is one that has electrical and pneumatic elements.
Manual fluid pumps to actuate separate hydraulic parking brakes on railroad vehicles are also disclosed in the prior art. Those parking brakes are connected to the brake beams and may or may not be independent of the main brake cylinder.
Some rail car users or operators may prefer to eliminate the use of cables to connect the brake cylinder to a multiplier lever because of brake system complexity and cost, or for other reasons. Users may also like to have additional options as to where the multiplier levers could be located or positioned as part of any parking brake system. The present invention addresses those concerns and interests.
The present invention is a parking brake for a rail vehicle having a brake cylinder and a piston in the brake cylinder responsive to forces to apply and release the brakes on the vehicle. The brake cylinder may have a pressure side and a non-pressure side. The parking brake further includes at least one off-center connecting rod extending though an opening in the brake cylinder and connected to or with the piston through that opening. The opening may be on the pressure or non-pressure side of the brake cylinder. The at least one off-center connecting rod may function as an anti-rotational rod. The parking brake also includes a force multiplier connected to or with the at least one rod. Further included is an actuator connected to or with the force multiplier for driving the force multiplier to provide the force to move the at least one rod and the piston to move the brakes to an apply position.
In this application, an element may be connected to or with another element, meaning that the connection may be direct or indirect regardless of whether the word xe2x80x9ctoxe2x80x9d or xe2x80x9cwithxe2x80x9d is used to describe the connection. Either xe2x80x9ctoxe2x80x9d or xe2x80x9cwithxe2x80x9d may be used herein, and they are interchangeable.
Other features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.